Ti(III) is a mild reducing agent of industrial importance. It has applications in the synthesis of organic compounds where a controlled and selective reduction of functional groups is desired.
Ti(III) sulfate in sulfuric acid is required as a so-called "re-attack" solution in the Sulfate Process for the production of pigment grade TiO.sub.2. A stream of Ti(III) must be introduced in order to assure that the iron present in the ilmenite (FeO.TiO.sub.2) ore being leached by sulfuric acid is kept in the ferrous form. In the ferrous state, the iron remains soluble through the purification of the titanium dioxide product. Thus, ferrous ion is washed away, and a white pigment free of any iron coloration results.
Common methods for the reduction of Ti(IV) to Ti(III).include the use of either metallic aluminum or metallic zinc. In sulfuric acid, such methods require organic inhibitors, to reduce the parasitic evolution of hydrogen. Difficulties with such approaches are obvious, especially from an environmental aspect.
Currently, the Sulfate Process has about a 15% market share of the titanium dioxide pigment production business. Hence a new, environmentally more benign process for Ti(III) reagent preparation produces retrofit opportunities throughout the industry.
Ti(III) salts also constitute effective reducing agents for organic compounds.